The present invention relates to a rotary potentiometer, particularly for measuring the angular position of a rotary element such as the throttle valve of an internal combustion engine.
Rotary potentiometers are known of the type having a stationary case provided on the inside with an electrical resistor defining a resistive track against which is applied a wiper carried by a rotor mounted in the case. The rotor is biased by a helical spring toward a rest position. The rest position is defined by a part of the rotor coming to rest against a stop portion of the case.
Rotation of the rotor causes the internal electrical resistance detected by the potentiometer to vary so that the ratio between the output and input voltages of the potentiometer is representative of the angle of rotation of the rotor in relation to its rest position. Measurement of this ratio can therefore be used in a potentiometric sensor to characterize the angular position of a rotary element in relation to a stationary point of reference.
In potentiometers of this type, during mounting of the rotor in the case, all contact must be avoided between the wiper and the resistive track to prevent damage thereto. This operation therefore is rather delicate and in the present state of the art requires an additional tool to be used to flatten the wiper against the rotor when the latter is being positioned in the case.